1. Field of the Invention
The present invention relates to a liquid crystal display device.
2. Description of the Related Art
In a liquid crystal display panel, a TN (Twisted Nematic) mode, a VA (Vertical Alignment) mode, and an IPS (In-Plane Switching)/FFS (Fringe Field Switching) mode are used. To meet a demand for a wide viewing angle and a high contrast, the VA mode and IPS/FFS mode are dominantly used. However, the responsivity in the VA mode and IPS/FFS mode is not sufficient, and there is a problem with moving image display. In addition, an OCB (Optically Compensated Bend) mode and a TBA (Transverse Bend Alignment) mode, which can improve responsivity and adapt to moving image display, have been proposed.
In the OCB mode, although high-speed responsivity is exhibited, a transition operation from a splay alignment, which is an initial alignment, to a bend alignment at a time of driving (e.g. application of a voltage of 10 V or more), is needed at a time of power-on, and a driving circuit for an initial transition is necessary, in addition to a normal driving circuit. Thus, the OCB mode leads to an increase in cost, and there is such a problem that the OCB mode is not suited to mobile devices in which there are restrictions to power supplies.
Furthermore, in the TBA mode, since a dielectric film is provided on a common electrode on a color filter substrate side, there is a problem that image persistence tends to easily occur due to a DC imbalance resulting from this dielectric film. Besides, since an oblique electric field is weak at a normal driving voltage (e.g. about 5 V), there is a problem that transmittance lowers.